Summary:
This gives some sense about how fast it is.
Background: I was trying to get rid of python-lz4, by exposing this to Python.
However, I noticed it's 10x slower than python-lz4. Therefore I added some
benchmark here to test if it's the wrapper or the Rust lz4 code.
It does not seem to be this crate:
```
# Pure Rust
compress (100M) 77.170 ms
decompress (~100M) 67.043 ms
# python-lz4
In [1]: import lz4, os
In [2]: b=os.urandom(100000000);
In [3]: %timeit lz4.compress(b)
10 loops, best of 3: 87.4 ms per loop
```
Reviewed By: DurhamG
Differential Revision: D13516205
fbshipit-source-id: f55f94bbecc3b49667ed12174f7000b1aa29e7c4